Botanical designation: Mentha arvensis L.
1. Field of the Invention
The origin of the mint plant of the present application is a single somaclonal variant of cultivar xe2x80x98Himalayaxe2x80x99 (U.S. Plant Pat. No. 10,935). The present invention relates to a novel, insect tolerant, high yielding essential oil and menthol yielding mint plant named xe2x80x98Sambhavxe2x80x99, which is derived from Mentha arvensis L.. The mint plant of the present invention has been developed as a result of planned experiments for the development of an insect tolerant mint plant with high oil and menthol yield which devised a procedure for early selection of somaclonal variants at the in vitro stage variety of Mentha arvensis. The plant of the present invention can be propagated vegetatively by suckers and is genetically stable for commercial cultivation. The plant type of the present invention is unique because it has an extra wide canopy and height surpassing all existing varieties. This allows for better sunlight capture and foliage production which ultimately produce high oil and menthol yield.
2. Description of Related Art
Mentha arvensis L. var piperescens Holmes (menthol or Japanese mint) is an industrial crop that is widely cultivated for its essential oil from which menthol is purified by crystallization through freezing. Menthol and other terpenoids present in the dementholated oil of Mentha arvensis are used in the food, perfumery and pharmaceutical industries. In the varietal improvement programme, the genetic alternations leading to the enhancement in the tolerance against pest and disease and improvement of other characteristics which improve the yield and quality of essential oil is most desirable. Insect tolerance is desired particularly against Spilarctia obliqua in Mentha arvensis L., one of the most damaging pests of mints in India. Since the mint plant is of considerable interest to the industrial world, programs for the isolation of desirable clones with improved terpene accumulation and suitable agronomic traits are being pursued in several laboratories. However, due to the inherent problem of seed setting in mints, conventional breeding programs are severely hampered. In vitro high efficiency procedures for cell and callus cultures and shoot regeneration from axillary buds and leaf explants have been reported in some species of the genus Mentha, especially the commercially important species M. piperata and M. spicata. However, in M. arvensis proliferation from limited explants such as nodes, terminal and axillary buds and distal segments of leaf petiole have relatively low levels of efficiency. There have been attempts to develop new varieties or genotypes by alternative methods like clonal selection, mutation breeding and somaclonal variation in mint plants (S. P. S. Khanuja, A. K. Shasany, S. Dhawan, S. Kumar, Rapid procedure for isolating somaclones of altered genotypes in Mentha arvensis. J Med. Aroma. Plant Sci. 20 (1998) 359-361.). Applicants have reported high efficiency protocols for rapid detection and selection procedures for development of somaclonal variants through molecular approaches in Mentha arvensis (S. P. S. Khanuja, A. K. Shasany, S. Dhawan, S. Kumar, Rapid procedure for isolating somaclones of altered genotypes in Mentha arvensis. J Med. Aroma. Plant Sci. 20 (1998) 359-361). Applicants have also successfully defined the condition and media to restrict the emergence of somaclonal variation for stable micropropagation purposes (A. K. Shasany, S. P. S. Khanuja, S. Dhawan, U. Yadav, S. Sharma, S. Kumar, High regenerative nature of Mentha arvensis internodes. Journal of Biosciences 23 (1998) 641646.).
For the present invention, Applicants utilize the already reported protocol (S. P. S. Khanuja, A. K. Shasany, S. Dhawan, S. Kumar, Rapid procedure for isolating somaclones of altered genotypes in Mentha arvensis. J Med. Aroma. Plant Sci. 20 (1998) 359-361.) to generate capture the somaclonal variations in larger frequencies. Applicants then screen the somaclones for their tolerance to Spilarctia obliqua by using a novel method for rapid and dependable selection of tolerant clone(s) at the tissue culture stage. The somaclones that were determined to be insect tolerant were then subjected to screening using instar larvae of lepidopteran insect pest Spilarctia obliqua. 
The selected tolerant pants are then tested for their stability, essential oil content, menthol content and biomass yield. Consequently, the plant xe2x80x98Sambhavxe2x80x99 was selected for unmatchable vigor of shoots, higher menthol production and increased insect tolerance through field evaluation.
Accordingly, the invention provides a novel mint plant of Mentha arvensis named xe2x80x98Sambhavxe2x80x99, which is developed employing tissue culture techniques, said plant of the present invention possessing the following combination of characteristics:
a. the plant is highly tolerant to foliage feeding insect pests, especially Spilarctia obliqua; 
b. the plant possesses vigorous and rapid vegetative growth with high regenerability covering at least a 85 cm canopy area and a height of at least 73.5 cm attained in a maximum of 100 days;
c. the plant has a distinct molecular profile by random amplified polymorphic DNA (RAPD) using 20 OPJ primers and 20 MAP primers which distinguishes the plant from the other existing varieties,
d. the plant shows tolerance to leaf spots, rust and powdery mildew as in the parent variety xe2x80x98Himalayaxe2x80x99,
e. the plant has the follows characteristics: light greenish leaves, whitish flowers with a distinct morphology of a single main stem with branches coming out of the lower nodes imparting a shape of up-side down open filled umbrella to the canopy allowing equal distribution of sunlight, thus prevents yellowing and fall of lower leaves;
f. the plant is able to produce the highest herbage when compare to the other control plants, and
g. the plant yields oil containing 75 to 80% menthol;
The plant of the present invention is developed through an unique, rapid in vitro screening method. This method is not limited to Mentha arvensis.